Adding a motor to a bike

Hello,
I was thinking about adding a 24v 250w dc brushless motor to a bike, to power it with 2 packs of 12v 10A Lithium Ion in series ( Batteria al litio polimerica Liitokala 12.6V 18000mAh 12v 18ah per allarme luce LED CCTV Cam Monitor DC 5.5*2.1mm|Battery Packs| - AliExpress? ), then connect the packs to this DC 5V-36V 15A 400W MOS FET:
DC 5V 36V 15A 400W MOS FET Trigger Switch Drive Module PWM Regulator Control Panel Motor Control Board 12V 24V High Power Module|Motor Driver| - AliExpress?
And provide the PWM from an arduino.
It seems too simple to me, am i missing something?
thanks

Hi,
The MOSFET module seems to have power terminals that are not adequate for your motor.
The MOSFET specs will be okay, but the complete mechanical assembly is nowhere near able to take the current.
mosfetmod.jpg
Do you have link to specs/data of the motor, in particular the stall current, this is very important to motor control design.

Have you googled arduino electric bicycle

Tom... :slight_smile:

mosfetmod.jpg

amadeok:
I was thinking about adding a 24v 250w dc brushless motor to a bike

Brushless motors are not powered the same way as a brushed motor. Typically you use a brushless ESC to drive it.

Motors that are driving large loads (like a bike and human) often spend a lot of time at stall or near stall, pulling a lot of current. Make sure your equipment can handle that.

vinceherman:
Brushless motors are not powered the same way as a brushed motor. Typically you use a brushless ESC to drive it.

Motors that are driving large loads (like a bike and human) often spend a lot of time at stall or near stall, pulling a lot of current. Make sure your equipment can handle that.

Good catch, I need more caffeine.... :slight_smile:

Hi,
thanks for replies, these are a few i've been seeing:
https://www.ebay.it/itm/24v-250w-Motore-Elettrico-Spazzolato-Per-Bici-Bicicletta-Scooter-E-Bici-Spazzola/223747685800?

https://www.ebay.it/itm/MY1016-Motore-spazzolato-DC-ad-alta-velocita-per-scooter-elettrico-24-V-300-W/202874520020?

https://www.ebay.it/itm/Motore-Elettrico-di-Riduzione-24V-DC-250W-2700-RPM-per-E-ATV-Bike-con-Controller/202940577581?hash=item2f4033772d:g:NCEAAOSwsKRedGNJ

Sorry but that PWM controller board says 400w and 15a, you mean that it's fake?

I've seen other like this: DC10 55V Regolatore di Velocità del Motore Elettrico di Controllo PWM Regolatore con Reversibile Unità Interruttore di Ingresso del Modulo 60A 12V 24V 36V 48V|Motor Controller| - AliExpress?
but this one has PWM built-in, would i be able to remove the pot it comes with and send PWM from the arduino?

amadeok:
Sorry but that PWM controller board says 400w and 15a, you mean that it's fake?

You need what is called an ESC, for your brushless motor.
ESC, Electronic Speed Controller.

The PWM controller is for a brushed DC motor.

The motor you are looking at is basically a 3phase AC motor and requires a special controller.

Have you googled? arduino electric bicycle brushless motor

Tom... :slight_smile:

TomGeorge:
You need what is called an ESC, for your brushless motor.
ESC, Electronic Speed Controller.

The PWM controller is for a brushed DC motor.

The motor you are looking at is basically a 3phase AC motor and requires a special controller.

Have you googled? arduino electric bicycle brushless motor

Tom... :slight_smile:

Sorry my bad, i meand brushed motor, not brushless. In fact all those i've seen are DC brushed motors.

Almost every online dealer e.g. Amazon, Ebay etc. seem to have some degree of gear which would suit your needs at a rather reasonable price also.

https://www.amazon.com.au/s?k=e+scooter+speed+control&i=sporting&ref=nb_sb_noss

The motors you linked are brushed DC motors. A mosfet can drive them. However...

You should determine the stall current of the motor. What is the resistance when you measure across the wires without any power connected? That will dictate how much current it will draw when it starts.

[For example, a little toy motor I have draws 0.45A at 12V. But the resistance is 3.3 Ohms when the motor is off. That means that when it starts, the initial current is 3.6A.]

For your motor, 250W at 24V is 10.4A. How much more capable should your controller be? I don't know, but probably somewhere capable of around a peak current of 60-80A.

Once you get into those currents and powers, mosfet switching becomes an issue. The slower a mosfet is switched (eg, by an arduino IO pin), the more heat it generates. When the mosfet is OFF (24V, 0A) then the power dissipated is 0W. When the mosfet is ON (0V, 10A), then the power it dissipates is also 0W. The problem is when it is turned on slowly, between fully on and fully off, there can be a great amount of power that is lost as heat. The arduino pin can only turn it on relatively slowly - it cannot push enough power to turn it on quickly and minimize the switching time.

My recommendation is to buy a ready-made motor controller for your motor. Something like this:

(note, it's rated for continuous 19A, which should be enough for your motor - the starting amps is not specified, although the individual mosfets that are on that board are capable of more than 100A)